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Re: Performance bug? Very large rev files

From: Daniel Berlin <dberlin_at_dberlin.org>
Date: 2007-03-29 20:37:25 CEST

On 3/29/07, Malcolm Rowe <malcolm-svn-dev@farside.org.uk> wrote:
> On Thu, Mar 29, 2007 at 04:04:16AM -0400, Rick Yorgason wrote:
> > For the last little while I've been diagnosing some very large rev files
> > for all of the commits of one of my files in a real-world repository,
> > and the db/rev files seem to be much bigger than they should be.
> >
> > I've posted some experiments in the users list, but I was hoping I could
> > get some attention from the devs. My latest post shows just how big
> > this issue can be:
> >
> > http://subversion.tigris.org/servlets/ReadMsg?list=users&msgNo=64261
> >
>
> I'm not sure whether this is the cause, but be aware that we compute
> the deltas using a window of 100K that moves (in 100K steps) through the
> reference and version files, so we can't take advantage of inter-window
> deltas. We do this to bound the memory usage of the compressor and
> decompressor, and it seems to be one of the most significant factors in
> our compression performance, especially if we ever want to start using
> some of the (theoretically) better delta algorithms.

Ya, we need to up the window size (to about a meg or two), but it's
hardcoded in some places that make it a not backwards compatible
change with more work.

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Received on Thu Mar 29 20:37:41 2007

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